Nature Based Solutions - Implementation Models Database

Urban green space management, Constructed wetlands and built structures for water management, Green roofs

The Avenue

A short description of the NSB

Completed in 2011, the Avenue has an active streetscape that has become a popular destination for visitors, office workers, residents, and students in downtown Washington. The project came out of an urban design study for the disused parcel that previously held the George Washington University Hospital, which was also Square 54 of the original Washington plan. The project is the result of a partnership between George Washington University and Boston Properties Inc. under a 60-year lease that has since provided funding for the construction of the university’s Science and Engineering Hall and contributed an estimated $11.5 million in annual city tax revenues. The ground lease terms were based on the amount of developable space rather than the possible floor/area ratio (FAR), which led the development team to create a courtyard concept slightly below FAR opportunities. A key requirement for the design of the building was a below-grade loading dock, which also created the opportunity for an interior courtyard above it. Sustainable design can be found throughout the Avenue. Green and lightly coloured roofs absorb less heat than conventional black roofs, thereby decreasing peak roof surface temperature by approximately 40 degrees Fahrenheit. The Avenue also uses a high-efficiency irrigation system and native and drought-tolerant plants, which reduce the amount of water needed by an estimated 62 percent. Main innovative water management features of The Avenue are: • Green roofs. An extensive 8.000-square-foot green roof is spread equally across the office and residential buildings. This green roof system comprises a water retention layer, a drainage layer, filter fabric, engineered soil and succulent plantings. On the residential roof, more than 300 linear feet of raised planters with tall evergreen hedges shield the pool and terraces from sight and wind. • Stormwater treatment and reuse system. Water is absorbed by the green roofs and then sent through interior piping into the stormwater filter, which includes two sand filters, an ultraviolet sterilizer, and an ionizer that kills algae, bacteria, and viruses without the use of extra chemicals. This system allows plants to grow directly in the water feature and requires less maintenance than a standard infiltration system.45 Water is then re-circulated into the 7.500-gallon cistern, which is located underneath the courtyard, within the five-level parking garage below. Irrigation water is pumped directly from the cistern, and all other stored rainwater is continuously pumped through the courtyard water feature and treatment system. The development’s robust stormwater management system for collecting, treating, and reusing rainwater in an inviting courtyard is able to manage an estimated 76.000 gallons of stormwater. • Courtyard water feature. The attractive water feature doubles as a stormwater container, holding roughly 15.000 gallons of water that has been re-circulated through the cistern and treatment system. The courtyard’s water feature is 100 percent supplied by reclaimed stormwater. The water feature includes aquatic vegetation in perforated planters that allow the roots to provide supplemental filtration.

NBS Implementation context
Location Washington, DC (USA)
Status (from - to) Project delivered (completed in August 2011)
NBS Scale Object (building, etc.) Neighbourhood
NBS Impacts scale Object (building, etc.) Neighbourhood City
Urban density/ Soil consumption High (dense city center)
NBS Typology


NBS Uban Challenges
Climate Issues Climate mitigation
Climate adaptation
Other 0
Urban water management and quality Urban water management and quality
Flood management
Other 0
Air Quality Air quality at district/city scale
Air quality locally
Other 0
Urban Space and Biodiversity Biodiversity
Urban space design
Urban space management
Other 0
Urban Regeneration and Soil Air quality at district/city scale
Other 0
Resource efficiency Food, energy and water
Raw materials
Waste
Recycling
Other 0
Public health and well-being Acustic
Quality of life
Health
Other 0
Environmental justice and social cohesion Environmental Justice: Recognition
Environmental Justice: Procedural Justice
Environmental Justice: Distributional Justice
Environmental Justice: Capabilities
Environmental Justice: Responsibility
Social Cohesion
Other 0
Urban planning and governance Urban planning and form
Governance in planning
Other 0
People Security Control of crimes
Control of extraordinary events
Other 0
Green economy Circular economy
Bioeconomy activities
Direct economic value of NBS
Other 0
Other
NBS Stakeholders & Governance

The project is the result of a partnership between George Washington University and Boston Properties Inc.

Initial actors (Leaders) Community Research institutions (George Washington University),Market Private sector (Boston Properties Inc.)
Involved actors Governments Local government/municipality, Community Research institutions,Market Private sector
Ecological scale Local scale green area
Governance model CLUSTER 2: New Public Management Public_private partnership (PPP)
NBS Financial aspects

The ground lease terms were based on the amount of developable space rather than the possible floor/area ratio (FAR), which led the development team to create a courtyard concept slightly below FAR opportunities.

Global (estimated) cost of the project more than 5M€ ($336 million, about €282.000 million)
Financing mechanism CLUSTER 1: Public financing,CLUSTER 4: PUBLIC-PRIVATE City Planning Regulations
NBS Business Models Archetype
Technological Create value from waste Substitute with renewables and natural processes
Social Non applicable
Organisational Non applicable
NBS Success and limiting factors
Process enablers
Knowledge -
Governance -
Economy Government support Provisioning of incentives to attract private investment, Create conditions for new business models and finance schemes
Process inibitors
Knowledge Technical inadequacy Lack of ready-to-apply scientific results, concepts and technologies
Governance -
Economy Perception of the benefits Short term vision, Budget constraints
IM Keywords
  • Public_private partnership (PPP)

  • Local scale green area

  • Public financing

  • City Planning Regulations

  • Create value from waste

  • Substitute with renewables and natural processes

References
www.sasaki.com/project/8/the-avenue/ uli.org/wp-content/uploads/ULI-Documents/The-Avenue.pdf landscapeperformance.org/sites/default/files/The%20Avenue%20Methodology_0.pdf